In recent years, an increase in a capacity and speed of networks is being requested. Therefore, data may be transmitted using an optical signal not only when a distance between nodes is long but also when a distance between nodes is relatively short.
FIG. 1 illustrates an example of an optical transmission system. In an example illustrated in FIG. 1, in a node A, a media access control (MAC) device 1a and an optical transceiver 2a are provided. Similarly, in a node B, a MAC device 1b and an optical transceiver 2b are provided.
The MAC device 1a stores input data in a frame of a specified format and guides the frame to the optical transceiver 2a. Further, the MAC device 1a extracts data from a frame that has been transmitted from a corresponding node. The optical transceiver 2a converts a frame generated by the MAC device 1a into an optical signal and transmits the optical signal to the corresponding node. Further, the optical transceiver 2a converts an optical signal received from the corresponding node into an electric signal and guides the electric signal to the MAC device 1a. The MAC device 1b and the optical transceiver 2b are substantially the same as the MAC device 1a and the optical transceiver 2a, and therefore descriptions are omitted.
In the optical transmission system having the above configuration, further speeding up of data transmission is requested. In recent years, a configuration in which data of about 100 Gbps is transmitted between nodes has been put into practical use. In addition, a configuration is being studied in which data of about 400 Gbps is transmitted between nodes.
However, as a transmission rate of data becomes higher, a bit error rate tends to become higher. In particular, increasing a speed of electrical circuits is not easy, and therefore when the transmission rate of data is high, a bit error tends to occur in an electrical interface. Therefore, a configuration in which a bit error is detected and corrected using a forward error correction (FEC) in the electrical interface is proposed. In an example illustrated in FIG. 1, in the node A, an FEC is added to a frame transmitted between the MAC device 1a and the optical transceiver 2a, and in the node B, an FEC is added to a frame transmitted between the MAC device 1b and the optical transceiver 2b. 
Related technology is described in the following document.
A 400 GbE Architectural Option, IEEE P802.3bs 400 Gb/s Ethernet Task Force, July 2014, San Diego
As described above, a configuration in which an error correction is performed using an FEC in the electrical interface is proposed. However, power consumption of a circuit in which the FEC is terminated is not small. For example, power consumption of a circuit in which 100G-KR4 is terminated is about 45 mW and power consumption of a circuit in which 100G-KP4 is terminated is about 105 mW.